The present invention relates generally to lighting techniques. More specifically, embodiments of the invention include techniques for manufacturing optical devices, such as light emitting diodes (LEDs) using a separation process of thick gallium and nitrogen containing substrates, such as GaN configured in non-polar or semi-polar crystalline orientations. The starting materials can include polar gallium nitride containing materials. The invention can be applied white lighting, multi-colored lighting, general illumination, decorative lighting, automotive and aircraft lamps, street lights, lighting for plant growth, indicator lights, lighting for flat panel displays, and other optoelectronic devices.
In the late 1800's, Thomas Edison invented the light bulb. The conventional light bulb, commonly called the “Edison bulb,” has been used for over one hundred years. The conventional light bulb uses a tungsten filament enclosed in a glass bulb sealed in a base, which is screwed into a socket. The socket is coupled to an AC power or DC power source. The conventional light bulb can be found commonly in houses, buildings, and outdoor lightings, and other areas requiring light. Unfortunately, drawbacks exist with the conventional Edison light bulb. That is, the conventional light bulb dissipates much thermal energy. More than 90% of the energy used for the conventional light bulb dissipates as thermal energy. Additionally, the conventional light bulb routinely fails often due to thermal expansion and contraction of the filament element.
Solid state lighting techniques are known. Solid state lighting relies upon semiconductor materials to produce light emitting diodes, commonly called LEDs. At first, red LEDs were demonstrated and introduced into commerce. Red LEDs use Aluminum Indium Gallium Phosphide or AlInGaP semiconductor materials. Most recently, Shuji Nakamura pioneered the use of InGaN materials to produce LEDs emitting light in the blue color range for blue LEDs. The blue colored LEDs led to innovations such as solid state white lighting, the blue laser diode, which in turn enabled the Blu-Ray™ (trademark of the Blu-Ray Disc Association) DVD player, and other developments. Other colored LEDs have also been proposed.
High intensity UV, blue, and green LEDs based on GaN have been proposed and even demonstrated with some success. Efficiencies have typically been highest in the UV-violet, dropping off as the emission wavelength increases to blue or green. Unfortunately, achieving high intensity, high-efficiency GaN-based green LEDs has been particularly problematic. Additionally, GaN based LEDs have been costly and difficult to produce on a wide-scale in an efficient manner.
Conventional LED fabrication process typically employ a wafer scribing and breaking procedure to separate individual LED chips within a wafer. The wafers are typically thinned to ˜100 um or less, and are typically laser- or diamond-scribed, on one side prior to dicing. Thinning often uses grinding and polishing techniques, which are time consuming and costly.